Differing aircraft wing designs are as old as flight itself, or perhaps older, considering the many designs penned by Michelangelo. Specifically, the Wright Brothers airplane in what is considered Man's first powered flight utilized wing warping for flight control. As ambition loaded wings more heavily in the years following, a fixed wing and movable control surfaces became the control means of choice. This trend has maintained until present day. Recently, NASA, among others, began exploring wing warp control for use in drones or unmanned air vehicles.
One such investigation is detailed in American Institute of Aeronautics and Astronautics (AIAA) paper 2007-5347. The investigation described a wing of a micro aircraft that had a shaft sewn into the leading edge, and as the shaft rotated, the wing was warped to provide aileron control. The present invention utilizes wing warp control, but combines this with retractable wing structure.
Retractable or deployable wings have also been described in various ways in the past. Most collapsible wings do so by folding in some fashion. Others have used inflatable wings to accomplish the removal of a wing structure when not needed or wanted. A few have provided extension devices to positively extend and keep a wing extended, whether fully extended or only partially extended. In this fashion, the wing could be extended fully for take-off, and then partially retracted while in cruise. While of obvious benefit, these latter wing extension devices add weight and complexity to aircraft that in the real world depend upon low weight and simplicity to operate. The intent of the present invention is to provide a lightweight retractable wing structure that is simple in design and operation.
Numerous examples exist of folded wing designs, most relating to automobiles being converted to flying craft. Molt Taylor's Air Car is a primary example, and one of the few that saw limited production. Most examples have detachable or folding wings. Another common example of folded wings exist in the aircraft intended for sea operations, as there is limited space on an aircraft carrier and folding wings aids dense aircraft storage. The Corsair was an example of this type of folded-wing design.
One example of a collapsing wing for a land/air vehicle is Robert O. Shertz, whose 1968 U.S. Pat. No. 3,371,886 shows a folded wing design that collapses the wing, one panel over top of another, but the wing panels are not nestled. Inventors Sarh and Branko disclose another example, with many similarities to the present invention, in U.S. Pat. No. 4,824,053. The inventors of this patent have a wing with panels that nestle together, but the nestling is accomplished by having threaded portions of a wing spar move in relation to portions that are not threaded to allow adjacent panels a means to mechanically collapse within each other. This raises the possibility of operating the aircraft with a partially extended wing, which may be advantageous in long-range cruising. The limitation of this design appears to be the lack of overlap between adjacent spar sections when fully extended, which dictates heavier spar sections and a heavy wing design. There is no mention of wing warping or other control mechanisms inherent in the design, nor any means of control being considered for practical use of such a wing.